Local: Solvent dyes are
insoluble in water but soluble in nonpolar organic solvents
and fats. It is
usually used as a solution in an organic solvent. Azo structure solvent dyes
are often responsible yellow-red color whereas anthraquinone structure
solvent dyes tend to be green-blue. Some other structures
for solvent dyes include heterocyclic rings, metal complex, pyrazolone, xanthene, and
ketoamine. Solvent dyes do not ionise. Solvent
dye, undergoing molecular rearrangement, is dissoluted in the substrate. It
colours and binds to the lipids resulting in showing colored regions. In
industrial field, it is used in coloring oils, waxes, greases, fats,
hydrocarbons derivatives, polishes, oily insecticides, and acrylic emulsions. Quinizarin Green, a
synthetic dye for greenish coloring
is used in coloring cosmetics and medications (D&C Green No.6).